What is the theme in Mutant Message Down Under by Marlo Morgan?

Another theme is is the manifestations of spirit. The essential purpose of the mythic journey described above is to introduce individuals (those taking the journey and those hearing/reading about it) to the ways and manifestations of spirit - in short, to bring him/her into a closer relationship to God, the Great Mystery, the Oneness, karma, or however the unknowable is known in whatever spiritual belief system.